LCD screen display principle

LCD screen display principle

1. Physical characteristics of liquid crystal

The physical properties of liquid crystal are: when it is energized, it is turned on and the arrangement becomes orderly, making it easy for light to pass; when it is not energized, the arrangement is chaotic, preventing light from passing. Let the liquid crystal block or allow light to penetrate like a gate. Technically speaking, the LCD panel contains two very delicate soda-free glass materials, called Substrates, with a layer of liquid crystal in between. When the light beam passes through this layer of liquid crystal, the liquid crystal itself will stand in rows or twist in an irregular shape, thus blocking or allowing the light beam to pass smoothly. Most liquid crystals are organic compounds, composed of long rod-shaped molecules. In the natural state, the long axes of these rod-shaped molecules are roughly parallel. When the liquid crystal is poured into a well-processed slotted plane, the liquid crystal molecules will be arranged along the grooves, so if the grooves are very parallel, the molecules are also completely parallel.

2. The principle of monochrome LCD

LCD technology is to pour liquid crystal between two planes lined with fine grooves. The grooves on these two planes are perpendicular to each other (intersect at 90 degrees). That is to say, if the molecules on one plane are aligned north-south, the molecules on the other plane are aligned east-west, and the molecules between the two planes are forced into a 90-degree twisted state. Since the light travels along the direction of the molecular arrangement, the light is also twisted 90 degrees when passing through the liquid crystal. But when a voltage is applied to the liquid crystal, the molecules will re-arrange vertically so that the light can be directed out without any twisting.

LCD relies on polarization filters (plates) and light itself. Natural light diverges randomly in all directions. The polarization filter is actually a series of increasingly thinner parallel lines. These lines form a net, blocking all light that is not parallel to these lines. The line of the polarization filter is exactly perpendicular to the first one, so it can completely block those polarized light. Only when the lines of the two filters are completely parallel, or the light itself has been twisted to match the second polarized filter, the light can penetrate. LCD is composed of two polarized filters that are perpendicular to each other, so under normal circumstances, all light that attempts to penetrate should be blocked. However, because the two filters are filled with twisted liquid crystals, after the light passes through the first filter, it will be twisted 90 degrees by the liquid crystal molecules, and finally pass through the second filter. On the other hand, if a voltage is applied to the liquid crystal, the molecules will rearrange and be completely parallel, so that the light is no longer twisted, so it happens to be blocked by the second filter. In short, the light is blocked when power is applied, and the light is emitted when the power is not applied.